This thread is very interesting.
I'm often having a question for the factor that effect the compressor speed vs
altitude.
Is it possible that :
-the higher it go, the lower temp it is, and hence the more
EGT margin that the engine could archive with out burning the turbine.
[I'm heard some old engine like JT8D use the EGT as the factor to determine
the maximum thrust output]
-The higher we go, the more ram air pressure [for a typical flight], and hence
the compressor can produce more pressure to turn the turbine and hence
higher compressor speed.
- Or the Fuel Control Unit always work to keep the Compressor ratio constant?
Best Regards